Single handle faucets, commonly referred to as mixer valves, that control the flow of both hot and cold water have seen vast consumer acceptance. The faucets are commonly constructed such that a handle or knob is movable in two distinct direction to adjust the mix of hot and cold water and to adjust the volume rate or flow.
Two basic types of single handle mixer valves that have seen wide commercial acceptance are plate valves and ball valves. A ball valve faucet is renowned for reliable and durable one piece valve construction that is easily assembled. The handle is rigidly fastened to the ball valve element with no intermediate moving parts to provide for a durable and reliable construction. A plate valve faucet on the other hand offers a drive mechanism that allows motion of the handle in two predefined directions that has found worldwide commercial acceptance. This internationally accepted handle motion allows for an orbiting motion of the handle about a fixed axis of the valve body and a rocking, i.e. pivoting motion about a axis that moves with respect to the valve housing as the handle orbits about the fixed axis. The moving axis is perpendicular to the fixed axis of the valve housing.
A characteristic of this type of handle motion allows for the faucet to be turned off and the mix ratio of hot and cold water to be remembered by the location of the handle so that when the faucet is turned back on, one has the option of obtaining the same mix of hot and cold water flow through the faucet. This type of motion has made plate valve faucet commercially successful even in view of the more complicated linkage necessary between the handle and plate valve element.
Recently, ball valves have been devised that allow the handle to operate in the same fashion as the above described plate type mixer valves. The system is disclosed in U.S. Pat. No. 4,449,551 issued to Lorch on May 22, 1984. Another system is disclosed in PCT application PCT/US91/07816 filed on Oct. 22, 1991 by Dr. Alfons Knapp and is incorporated herein by reference. These systems combine the advantage of an ergonomic desirable handle motion with the high reliability of a ball valve faucet design.
Besides reliability of the faucet, a mixing valve must possess other characteristics to be commercially acceptable. The maximum flow rate must be sufficiently great and the noise level of operation must be sufficiently low. Another characteristic is that the faucet must operate in an ergonomic friendly or intuitive way. The ergonomic friendly characteristic has several identifiable qualities. Firstly, the flow rate and temperature mix must be predictable based on continuous motion of the handle. No abrupt or sudden changes in either flow rate or temperature mix is acceptable based on small amounts of motion of the handle. It is desirable that when the temperature mix is adjusted, the flow rate remain approximately constant. On the other hand, when the flow rate is adjusted, substantial, sudden and unpredictable temperature change is not acceptable. A dead zone at the cold end of the handle motion should exist where no mixing of hot water occurs for a limited angular motion of the handle from the full cold position.
It is desirable that a comfort zone exist whereby in a mixed position, an area of greater movement of the handle is needed to produce a predetermined temperature change as compared to handle movement in the hot or cold region. The comfort zone allows the faucet to be more finely adjusted when the temperature is within a certain range. As such, the graph profile of the handle motion plotted against temperature of discharged water resembles an s-curve. However, the comfort zone must not be overly flat, otherwise insufficient change of temperature occurs and an operator then overcompensates with excessive handle motion thereby leaving the comfort zone and receive surprising temperature changes in the discharged water. The handle motion for volume at a predetermined comfort temperature also desirably produces no temperature change.
The above desirable qualities must all be achieved by choosing the proper size ball valve element, defining the drive motion of the handle to adjust volume and temperature of the ball valve element, and prescribing the range of angular and rotational motion for the two defined drive motions of the handle. The correct locations and configurations of the inlet ports of the valve housing and the inlet openings of the ball valve element also provide the above desirable qualities.
The selection of the size of the ball is relatively constrained by the balancing desires of reducing the size of the faucet body and providing for adequate water flow through the valve element. The prescribed drive motion for the handle by commercial desirability is angular motion about a vertical axis substantially for temperature change and rocking motion about a horizontal axis substantially for flow rate adjustment. The range of motion for angular temperature change is limited by ergonomics to a maximum of one hundred and eighty (180) degrees and desirably in the range of ninety (90) degrees. Therefore, the qualities of a desirable faucet with no sudden temperature changes or volume changes and a desirable comfort zone with predictable flow rate and temperature changes in the operation of the mixing valve are most expeditiously achieved and adjusted by the proper selection of the size, location and configurations of the inlet ports in both the housing and inlet openings in the ball valve.
What is needed is ball valve for a faucet mixing valve that has the commercially desirable drive motion that is easy to install and provides for longevity of the existing sealing elements.
What is also needed is a single handle mixing valve for a faucet that incorporates a ball valve with shaped inlet openings that provide for intuitively predictable flow rates and temperature of the discharged water therethrough.